WASHINGTON — As the most caustic campaign in modern American history nears its close, Hillary Clinton has built a formidable lead over Donald Trump approaching 10 percentage points, a USA TODAY/Suffolk University Poll finds. But she faces a deeply divided nation that is alarmed about the prospect of Election Day violence and what may be ahead.

A 51% majority of likely voters express at least some concern about the possibility of violence on Election Day; one in five are "very concerned." Three of four say they have confidence that the United States will have the peaceful transfer of power that has marked American democracy for more than 200 years, but just 40% say they are "very confident" about that.

More than four in 10 of Trump supporters say they won't recognize the legitimacy of Clinton as president, if she prevails, because they say she wouldn't have won fair and square.

"I have no idea who is rigging it, (but) there's just too many inconsistencies coming from all directions," says William Lister, 71, a Pittsburgh Democrat who is voting Republican for the first time to support Trump. He was among those polled. His advice: "I think everyone should vote on paper ballots this year."

Clinton supporters overwhelmingly reject the idea that the vote count can't be trusted. "It's 2016, and to be able to rig an election would be impossible at this point," scoffs Jennifer Neugebauer, 36, an orthodontic technician from Philadelphia and a Clinton enthusiast since her first presidential bid eight years ago.

"I don't think it's so much rigged against him," says Zachery Prickett, 21, of Delavan, Wis., who is supporting Jill Stein of the Green Party. "I think he destroyed his own campaign at this point."

The paradox for Clinton is that she is amassing a solid lead even as unprecedented challenges that could make governing more difficult come into sharp relief.

She now leads Trump among likely voters by 47%-38% in a four-way race. (Without rounding, she leads by 9.80 points, 47.40%-37.60%.) Support for third-party candidates has been cut in half since late August, a trend that is common for as voting nears. Libertarian Gary Johnson has dropped to 4% and Stein to 2%.

That said, the mood of the electorate is nothing like the optimism of three decades ago, when Reagan's gauzy re-election theme was "Morning in America."

"Since the polls are starting to shift quite a bit towards Hillary Clinton, I've been buying a lot more ammunition," says Rick Darling, 69, an engineer from Harrison Township, in Michigan's Detroit suburbs. In a follow-up phone interview after being surveyed, the Trump supporter said he fears progressives will want to "declare martial law and take our guns away" after the election.

"You can say I'm wearing my tin-foil hat," Darling says. "I don't know what's going to happen. It's so unpredictable. The country is so divided. I'm going to be prepared. If it all falls apart, I'm going to be ready if I have to be. I'm going to be a good Boy Scout."

A rigged election?

More than two-thirds of Trump voters say they worry the election returns could be manipulated. In contrast, eight in 10 of Clinton voters say the returns can be trusted to be fair and accurate.

Trump supporters overwhelmingly identify the primary threat as the news media, followed by the national political establishment. Just 3% say the chief threat is from foreign interests such as Russian hackers, which U.S. intelligence agencies accuse of leaking thousands of Democratic emails.

Few in either camp believe the news media is objective in this election.

By nearly 10-1, all those surveyed say the news media, including major newspapers and TV stations, would like to see Clinton rather than Trump elected. That includes 82% of Trump supporters and 74% of Clinton supporters. Six in 10 Trump supporters say the news media is coordinating stories with individual campaigns, rather than acting on its own accord. Three in 10 of Clinton supporters feel that way.

"When I was a kid, we watched the news; we would see what happened, and now it's what they want you to see." says David Zigerman, 55, a Trump supporter from North Palm Beach, Fla. "There's no gray area in wondering whether the media is biased."

Conflicts ahead

Both candidates are being dented by controversies:

• Trump has been hurt by allegations from about a dozen women of sexual harassment and assault, which he flatly denies. A 51% majority of those surveyed say they believe the women are telling the truth; just a third say they are lying to hurt the Republican candidate's campaign.

More than four in 10 say the accusations make them less likely to support the billionaire businessman and reality TV star. "I don't think it's made-up; I don't think it's politically driven," says Ben Rodemeyer, 38, an undecided voter from Denver who was among those surveyed. "I think that shows the character of the man."

The allegations that Trump groped women prompted Andrea Lynch, 61, to reach out to her daughters. "It did make me call my three daughters and say, 'If I did not tell you this goes on in the world, I'm very sorry,' " says Lynch, a Clinton supporter who lives in Malvern, Pa., in the crucial Philadelphia suburban county of Chester. "Except for the youngest, who is just a year out of college, the other two said they've already been there."

• Clinton has been hurt by the Wikileaks disclosure of thousands of emails from top advisers.

More than a third of those polled say excerpts of high-priced speeches she delivered to Wall Street bankers, including suggestions that she took different positions in public and private, make them less likely to support her. A 56% majority say emails that detail the intertwined relationships among the Clinton Foundation, its big donors and the State Department would raise questions about conflicts of interest for Clinton if she is elected to the White House. Even three in 10 of her own supporters see conflicts of interest ahead.

"It does bother me," says James Rogers, 50, a Clinton supporter from Raleigh, N.C., who works in real estate. Still, he adds, "That particular transgression is not as bad as the lack of decorum and potential flying off the handle that Donald Trump represents."

Rogers finds himself struggling not be to drawn into the political strains he sees. "There seems to be a lack of tolerance for opposing opinions," he says. "You can hang some of it as being politics as usual, but it seems that the country is so much more divisive than it has been in elections past."

He's not alone: Nearly six in 10 say divisions in the country are deeper than they were in the past. He and others worry if the nation will be able to come together after the election.

"I would love to say 'yes' and that would be to the benefit of everyone in this country, but, no, I don't think so," Zigerman says. "The divide is so vast."

Margaret Womack, 76, of Newport News, Va., is an avid supporter of Trump who labels Clinton a liar. "She will say anything or do anything to get the vote," says Womack, a retired administrative assistant at the College of William and Mary's Department of Theology.

What if Clinton wins?

"We'll have to stand behind her; we won't have a choice," she says unhappily. "I'll just pray for her to be honest, which God will have his hands full."